electrical water pump causing issues!

[miniminor63]

Hi

Everything is going well with the install, except for one major thing. I have a meziere electrical waterpump mounted  besides my A series engine in the mini. It is fairly close to the VR sensor (about 15 cm away), but the VR sensor use properly shielded cable that is connected to the grounds on the ECU. I have used this VR sensor and cable with megajolt before with no issues.

The waterpump is programmed to always be on in megatune (via a relay), its grounded about 20 cm away from the ECU ground together with the fan ground. Engine does not have a ground cable as its solid mounted to the car.

When I power up the VEMS the waterpump and fuel pump starts (fuel pump is set to be on for 3 secs after power up). but it does not turn off, also the injectors are clicking and filling my engine with fuel. the COPs also seem to be igniting the spark plugs. ALso I get trigger error warnings in megatune (red square down low on the screen).

If I disable the waterpump everything is fine and the engine starts and runs...

What could I do to solve this? I am going on the rollers very soon so need this fixed!

Thanks!

EDIT:

I have also tried to run a ground from the common ground for the VEMS to the battery (disconnecting it from where it was connected  to  the car), and also to run the waterpump from a totally separate battery (connected both plus and minus of the pump directly to the separate battery. Problem is still there when the VEMS is turned on.

[rob@vems.co.uk]

it does sound like the VR sensor is picking up the waterpump's noise.
What resistance is the VR sensor?
What serial number is your board?

[Jorgen]

Did you build your own ECU?

In any case we have seen this happen when a high impendance VR sensor is used or when there is no load on the sensor input.

We normally fit a 18k resistor between 5v and ground inside the ECU for VR applications to avoid this and to improve the signal quality in general.

Our ECU has an advanced VR input that will adapt to the signal strength, in it's base setting it will adapt to a fairly weak signal but this can be changed in a number of ways. One of which is mentioned above.

You should start by measuring the DC voltage on the trigger input with the ignition on, pump turned off and with the engine off.

You should also measure the resistance of the VR sensor (with it unplugged.)

Jörgen Karlsson
Gothenburg, Sweden.

[miniminor63]

VR resistance 380 ohm (ford EDIS one)

I measured the voltage at the wire where it connects to the VR,and it showed 0.46 volt.

[miniminor63]

the 0.4 volt doesnt sound promising thinking about it... P259 still works...

[miniminor63]

went out and measured it directly at the pin, 0.47 volt there also.... the other needing ones have 5 volt though (TPS).

[rob@vems.co.uk]

The pull-up that Jorgen referred to will mean that theres a slight voltage across the VR pins, so 0.4v is not unexpected.  The next task will be to start to raise this voltage using smaller resistors to pull the voltage on the VR input line up higher in order to kill the noise caused by the pump.
If you've followed the Subaru triggering thread you'll see that Skassa used a variable resistor to find the value for the pull-up resistor, I'd use one of those or a trim pot between 5v and VR signal pins, start with a high resistance and lower it until the pump noise is ignored, then start your cranking tests.

[miniminor63]

oh, I had not planned this

So, which pins should I solder this to?Between EC-36 pin27 and 29?



(I guess its okay to solder it between the  pins on the EC connectors inside the box?)?

[miniminor63]

also, would it help to turn filtering on?

I also have a hall sensor available, would it possibly help to just change to that?

[miniminor63]

problem goes away as soon as it is running, so think I will set the waterpump up to start at 30 degrees and call it okay for the time being:) Its never 30 degrees outside in Norway

[rob@vems.co.uk]

We all plan for our installs to go smoothly without problems, yet somehow they never do!

EC36pin27 and 29 is the place to have the pull-up, a pull-down (not usually recommended) would be between EC36pin27 and 26.
And its best done outside the box when experimenting (and probably best to keep it outside the box afterwards.  If those of us doing support had our way we'd never see another 'kit' sold).

A Hall sensor is cleaner but has other possible trigger setup problems.
Filtering will not help, it turns on a load of additional trigger settings that I've never seen work.

The fact that it goes away when running is great, it points towards the noise causing the VR sensor chip to false trigger and solves this problem.

But...

What happens when you try a hot start?  The pump will be on because the coolant temp is above 30deg.

Which will cost you time and money if you get problems when you're on the rollers.

For a quick and dirty fix, try a 10K, 5K and 1K pull-up and check your cold cranking.